Heat transfer systems and methods

ABSTRACT

Heat transfer apparatuses and systems are provided. A heat transfer apparatus ( 100 ) can include a thermal conduit ( 110 ) having a first end ( 120 ) and a second end ( 130 ). The thermal conduit can be disposed at least partially within an electronic device enclosure ( 140 ). A non-heat conductive material ( 150 ) can be disposed at least partially about at least a portion of the thermal conduit.

BACKGROUND OF THE INVENTION Description of the Related Art

Thermal management in compact electronic devices presents significantchallenges. As dock rates of central processing units and otherintegrated circuit based devices increases and the overall footprint ofthe devices housing those IC based devices decreases, heat rejectionfrom within the enclosure surrounding the electronic device becomesdifficult. Heat pipes and vapor chambers are two solutions used totransfer heat from a heat producing device to a heat rejecting device.However, the heat conveyed by heat pipes and vapor chambers can beradiated along the route of the heat pipe, prior to arriving at the heatdissipating device. This radiation can affect components proximate theheat pipe and, in some circumstances can also cause hot spots on theenclosure surrounding the electronic device.

SUMMARY OF THE INVENTION

A heat transfer apparatus is provided. A heat transfer apparatus caninclude a thermal conduit having a first end and a second end. Thethermal conduit can be disposed at least partially within an electronicdevice enclosure. A non-heat conductive material can be disposed atleast partially about at least a portion of the thermal conduit.

As used herein, a material referred to as a “non-heat conductivematerial” can refer to any material having a relatively low coefficientof thermal conductivity, i.e. a thermal insulator. A non-heat conductivematerial can include any material suitable for preventing conductiveheat transmission, convective heat transmission, radiant heattransmission, or any combination thereof. A non-heat conductive materialcan include rigid materials, semi-rigid materials, or flexiblematerials. Exemplary non-heat conductive materials can include, but arenot limited to, asbestos, carbon fiber, silica, diatomaceous earth,cork, wool, cotton, plastics, fiberglass, mineral wool, polystyrene,combinations thereof, and the like.

A heat transfer method is also provided. The method can includedisposing a non-heat conductive material about at least a portion of athermal conduit. The thermal conduit can be a hollow, sealed memberhaving a first end and a second end. The method can further includethermally connecting the first end of the thermal conduit to a heatproducing electronic device. The method can also include thermallyconnecting the second end of the thermal conduit to a heat dissipatingdevice.

As used herein, entities that have a “thermal connection”, or entitiesreferred to as “thermally connected”, refer to two or more entitiesbetween which energy in the form of heat, i.e. thermal energy, may betransmitted, transported, conveyed, or otherwise communicated.Typically, a thermal connection includes a physical interface betweenthe entities, however it is to be noted that a thermal connection may beestablished between two entities via the use of one or more conduitssuitable for the transmission of thermal energy linking the entities. Inone or more embodiments, the one or more conduits can be a solid orhollow conduit having a high coefficient of thermal conductivity. In oneillustrative example, two entities can be thermally operably connectedby mere proximity thereby permitting direct conductive heat transfer, orphysically remote entities can be thermally connected using one or moreconduits adapted to transfer all or a portion of the heat from oneentity to another entity.

A heat transfer system is also provided. The system can include a heatproducing electronic device and a heat dissipating device, each disposedat least partially within an electronic device enclosure. A thermalconduit having a first end and a second end can also be at leastpartially disposed within the electronic device enclosure. A non-heatconductive material can be disposed at least partially about at least aportion of the thermal conduit. The first end of the thermal conduit canbe thermally connected to the heat producing electronic device, and thesecond end of the thermal conduit can be thermally connected to the heatdissipating device.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of one or more disclosed embodiments may become apparent uponreading the following detailed description and upon reference to thedrawings in which:

FIG. 1 depicts an upper perspective view of an exemplary heat transferapparatus, according to one or more embodiments described herein;

FIG. 2A depicts a schematic diagram showing an illustrative heat flow inan exemplary heat transfer apparatus, according to one or moreembodiments described herein;

FIG. 2B depicts a schematic diagram showing an illustrative heat flow inanother exemplary heat transfer apparatus, according to one or moreembodiments described herein;

FIG. 3 depicts a plan view of an illustrative heat transfer system,according to one or more embodiments described herein.

DETAILED DESCRIPTION

FIG. 1 depicts an upper perspective view of an exemplary heat transferapparatus 100, according to one or more embodiments. The exemplary heattransfer apparatus 100 can include a thermal conduit 110 having a firstend 120 and a second end 130. The thermal conduit 110 can be partiallyor completely disposed within an electronic device enclosure 140. Anon-heat conductive material 150 can be at least partially disposedabout at least a portion of the thermal conduit 110. The thermal conduit110 can be thermally connected to a heat producing device 160 at thefirst end 120, and to a heat dissipating device 170 at the second end130.

The thermal conduit 110 can include one or more systems, devices, orcombination of systems and devices suitable for conducting, transferringor otherwise transmitting all or a portion of the thermal energyinputted at the first end 120 to the second end 130. The thermal conduit110 can have any physical shape or geometry. The thermal conduit 110 canbe a solid or hollow member. In one or more embodiments, the thermalconduit 110 can be a sealed hollow member having an internal structure,for example a heat pipe or vapor chamber having a wick and phase-changeheat transfer fluid disposed therein. In one or more embodiments, thethermal conduit 110 can be a material having a high thermalconductivity, for example an aluminum or aluminum alloy conduit having athermal conductivity of about 250 Watts/meter-Kelvin (W/m-K) or more; ora copper or copper alloy having a thermal conductivity of about 400W/m-K or more.

In one or more embodiments, the thermal conduit 110 can transfer all ora portion of the thermal energy or heat input at the first end 120 tothe second end 130 by conduction, e.g. by maintaining the second end 130at a temperature less than the temperature of the first rend 120. In oneor more embodiments, the thermal conduit 110 can transfer all or aportion of the thermal energy or heat input at the first end 120 to thesecond end 130 by convection, e.g. by transferring at least a portion ofthe heat input to a fluid within the thermal conduit that flows from thefirst end 120 to the second end 130 and returns. In one or moreembodiments, the thermal conduit can transfer all or a portion of thethermal energy or heat input at the first end 120 to the second end 130by a combination of conduction and convection.

The electronic device enclosure 140 can include devices, systems, or anycombination of systems and devices suitable for partially or completelyhousing the thermal conduit 110. In one or more embodiments, theelectronic device enclosure 140 can include any structure suitable forpartially or completely housing an electronic device, for example aportable computer, a laptop computer, a netbook, an ultraportablecomputer, a cellular device, a personal digital assistant (“PDA”), ahandheld gaming system, or the like. The electronic device enclosure 140can be any metallic or non-metallic material. Suitable metallicmaterials can include, but are not limited to, aluminum, magnesium,titanium, and the like. Suitable non-metallic materials can include, butare not limited to, polystyrene, acrylonitrile butadiene styrene(“ABS”), carbon fibre, and the like.

In one or more embodiments, one or more of the thermal conduit 110, theheat producing device 160, and the heat dissipating device 170 can bedisposed proximate all or a portion of the electronic device enclosure140. Radiant heat emitted by the thermal conduit 110 can cause anincrease in the surface temperature of the portion of the electronicdevice enclosure 140 proximate the thermal conduit 110.

To minimize or eliminate the increase in electronic device enclosure 140surface temperature proximate the thermal conduit 110, in one or moreembodiments, a non-heat conductive material 150 can be partially orcompletely disposed about all or a portion of the thermal conduit 110.In one or more embodiments, the non-heat conductive material 150 caninclude a coating bonded or otherwise partially or completely disposedabout all or a portion of the thermal conduit 110. In one or moreembodiments, the non-heat conductive material 150 can include a sleeve,sock, or similar structure into which all or a portion of the thermalconduit 110 can be inserted.

In one or more embodiments, the non-heat conductive material 150 caninclude one or more strips disposed helically about all or a portion ofthe thermal conduit 110, as depicted in FIG. 1. In one or more specificembodiments, the non-heat conductive material 150 can include one ormore continuous strips of woven silica, fiberglass, or mineral wooltape, e.g. automotive type “header tape” disposed spirally or helicallyabout all or a portion of the thermal conduit 110. In one or morespecific embodiments, the non-heat conductive material 150 can includeone or more continuous strips of foil-backed woven silica, fiberglass,or mineral wool tape disposed helically about all or a portion of thethermal conduit 110. In one or more specific embodiments, the thermalconductivity of the non-heat conductive material 150 disposed about thethermal conduit 110 can be about 1 W/m-K or less; about 0.5 W/m-K orless; about 0.1 W/m-K or less; or about 0.05 W/m-K or less.

In one or more embodiments, the first end 120 of the thermal conduit 110can be thermally connected to a heat producing device 160. The heatproducing device 160 can include, but are not limited to, an electroniccircuit, an integrated circuit, a frictional heat producing device, orany other device capable of producing thermal energy as a direct productor by-product of operation. In one or more specific embodiments, theheat producing device 160 can be an integrated circuit disposed within acomputing device. Exemplary heat producing integrated circuits foundwithin computing devices can include, but are not limited to, centralprocessing units (CPUs); solid state storage devices such as randomaccess memory (“RAM”); dynamic random access memory (“DRAM”); permanentdigital storage media such as memristors; graphical processing units(“GPUs”); and the like. In one or more embodiments, the first end 120 ofthe thermal conduit 110 can be directly chemically bonded or otherwiseattached to the heat producing device 160 via one or more heat transfermastics or the like. In one or more embodiments, the first end 120 ofthe thermal conduit 110 can be directly or indirectly mechanicallybonded or otherwise attached to the heat producing device 160, forexample using mechanical tension, or threaded fasteners.

In one or more embodiments, the second end 130 of the thermal conduit110 can be thermally connected to a heat dissipating device 170. Theheat dissipating device 170 can include systems, devices, or anycombination of systems and devices suitable for rejecting all or aportion of the thermal energy supplied to the heat dissipating device170 via the thermal conduit 110. In one or more embodiments, the heatdissipating device 170 can include one or more passive heat dissipatingdevices, for example an air-cooled radiator such as an extended surfaceheat exchanger. In one or more embodiments, the heat dissipating device170 can include one or more actively cooled heat dissipating devices,for example an air mover discharging across all or a portion of anair-cooled radiator, or a radiator cooled using a pumped liquid.

FIG. 2A depicts a schematic diagram showing an illustrative heat flow inan exemplary heat transfer apparatus 200A, according to one or moreembodiments. In one or more embodiments, heat produced by the heatgenerating device 160 can flow 210 to the first end 120 of the thermalconduit 110. Once transferred to the thermal conduit 110, heat can flow220 along the thermal conduit to the second end 130. A portion of theheat flow 220 through the thermal conduit 110 can be lost as radiantheat 230 emitted from the elevated temperature surface of the thermalconduit 110. Upon reaching the second end of the thermal conduit 110,heat can flow 240 to the heat dissipating device 170. Within the heatdissipating device 170, all or a portion of the heat transferred orconveyed from the thermal conduit 110 to the heat dissipating device 170can be rejected or otherwise emitted 250 from the heat dissipatingdevice 170.

In operation, an adiabatic zone 260 can form proximate all or a portionof the exterior surface of the thermal conduit 110. The adiabatic zone260 is a zone having very little or no thermal gradient or temperaturedifference that exists between the thermal conduit 110 and the fluid orambient environment surrounding the thermal conduit 110. The actualradiant heat 230 emitted by the thermal conduit 110 flows from thisadiabatic zone 260 to the fluid or ambient environment surrounding thethermal conduit 110.

The surface temperature of the thermal conduit 110 can increase as heatis transferred away from the heat producing device 160 to the heatdissipating device 170. A portion of the heat flow 220 through thethermal conduit 110 can be emitted from the exterior surface of thethermal conduit 110 as radiant heat 230. Where the thermal conduit 110may be disposed proximate heat sensitive components, or where thethermal conduit 110 may be proximate an exterior wall of the electronicdevice enclosure 140, such radiant heat 230 can cause an unacceptabletemperature increase. For example, where the thermal conduit 110 isdisposed proximate the bottom surface of a laptop or portable computer,the temperature increase of the bottom surface of the computer can makeit uncomfortable or impossible to rest the computer on a user's legs.

FIG. 2B depicts a schematic diagram showing an illustrative heat flow inanother exemplary heat transfer apparatus 200B, according to one or moreembodiments. The exemplary heat transfer apparatus 200B depicted in FIG.2B is similar to the exemplary heat transfer apparatus 200A depicted inFIG. 2A with the exception that a non-heat conductive material 150 hasbeen disposed about a portion of the thermal conduit 110.

In operation, in one or more embodiments, the non-heat conductivematerial 150 can be disposed about the thermal conduit 110 in the regionformerly occupied by the adiabatic zone 260 (ref. FIG. 2A). Since thetransmission of heat through the non-heat conductive material 150 isretarded or eliminated, the surface temperature of the non-heatconductive material 150 can generally be less than the surfacetemperature of the underlying thermal member 110. The lower surfacetemperature of the non-heat conductive material 150 can result in alower temperature adiabatic zone 280 forming proximate the non-heatconductive material 150. In turn, the lower temperature adiabatic zone280 can reduce the overall amount or quantity of radiant heat 270emitted to the fluid or ambient environment surrounding the thermalmember 110 by the system 200B.

Thus, as a consequence of the disposal of the non-heat conductivematerial 150 about the thermal conduit 110, the radiant heat 270 can beless than the radiant heat 230 emitted from the thermal conduit 110 inthe absence of the non-heat conductive material 150. In one or moreembodiments, the reduced heat loss from the thermal member 110 to thesurrounding environment can increase the operating temperature of theheat-dissipating device 170, thereby improving the overall efficiency ofthe heat-dissipating device 170. Improving the efficiency of theheat-dissipating device 170 can permit the use of physically smallerheat-dissipating devices 170, thereby freeing additional space withinthe electronic device enclosure 140.

Additionally, by reducing the quantity and intensity of the radiant heat270 emitted from the thermal conduit 110, the heat transmitted to nearbycomponents or to the electronic device enclosure 140 can be minimized oreliminated. Minimizing the radiant heat 270 emitted by the thermalconduit 110 can, for example, minimize or eliminate the temperature riseof the electronic device enclosure 140, thereby improving user comfortwhen resting the computer on a user's legs.

FIG. 3 depicts a plan view of an illustrative heat transfer system 300,according to one or more embodiments. In one or more embodiments, thesystem 300 can include a thermal conduit 110 having a first end 120 anda second end 130 disposed at least partially within an electronic deviceenclosure 140. A non-heat conductive material 150 can be disposed aboutthe exterior surface of at least a portion of the thermal conduit 110.The first end 120 of the thermal conduit 110 can be thermally connectedto a heat producing device 160, for example a CPU as depicted in FIG. 3.The second end 130 of the thermal conduit can be thermally connected toa heat dissipating device 170, for example a passive parallel finradiator as depicted in FIG. 3. An air mover 310 can be disposedproximate the heat dissipating device 170 such that at least a portionof the discharge airflow 320 passes over, through, or about the heatdissipating device 170. In one or more embodiments, the thermal conduit110, heat producing device 160, heat dissipating device 170, and airmover 310 can, be disposed on a substrate 330, for example a computermotherboard disposed within the electronic device enclosure 140.

In one or more embodiments, the heat producing device 160 can be aboard-mount or socket-mount central processing unit disposed in alaptop, or portable computing device. Although the thermal conduit 110is depicted as being thermally connected to only one heat producingdevice 160, any number of heat producing devices 160 can be similarlythermally connected to the thermal conduit 110 using one or more“branches.” For example, in one or more embodiments, a GPU and one ormore memory modules can also be thermally connected to the thermalconduit 110. Heat generated by the heat producing device 160 can betransmitted via the thermal conduit 110 to the heat dissipating device170 where the airflow 320 provided by the air mover 310 can remove orotherwise dissipate the heat transported by the thermal conduit 110.

In one or more embodiments, the thermal conduit 110 can be a vaporchamber having a wick and a heat transfer fluid disposed therein. Usinga vapor chamber, heat from the heat producing device 160 can vaporize aportion of the heat transfer fluid contained in the wick disposed withinthe thermal conduit 110 proximate the heat producing device 160. Thevaporized heat transfer fluid can flow via the thermal conduit 110 to apoint proximate the heat dissipating device 170. As the vaporized heattransfer fluid is cooled by the heat dissipating device 170, at least aportion of the heat transfer fluid can condense and be absorbed into thewick disposed within the thermal conduit 110 proximate the heatdissipating device 170. The condensed heat transfer fluid can flow viacapillary action through the wick back to a location proximate the heatproducing device 160 where the vaporization/condensation cycle can onceagain occur.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges from any lower limit to any upper limit arecontemplated unless otherwise indicated. Certain lower limits, upperlimits and ranges appear in one or more claims below. All numericalvalues are “about” or “approximately” the indicated value, and take intoaccount experimental error and variations that would be expected by aperson having ordinary skill in the art.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A heat transfer apparatus comprising: a thermal conduit having afirst end and a second end; wherein the thermal conduit is disposed atleast partially within an electronic device enclosure; and a non-heatconductive material disposed at least partially about at least a portionof the thermal conduit.
 2. The apparatus of claim 1, wherein the thermalconduit comprises a hollow, sealed, metallic member.
 3. The apparatus ofclaim 1, wherein the non-heat conductive material is selected from thegroup of materials consisting of: a woven fiberglass material, a wovensilica material, a woven mineral wool material, a foil backed wovenfiberglass material, a foil backed woven silica material, and a foilbacked woven mineral wool material.
 4. The apparatus of claim 1, whereinthe non-heat conductive material comprises a coating disposed about thethermal conduit.
 5. The apparatus of claim 1, wherein at least a portionof the first end of the thermal conduit is thermally connected to aheat-producing device.
 6. The apparatus of claim 1, wherein at least aportion of the second end of the thermal conduit is thermally connectedto a heat-dissipating device.
 7. A heat transfer method comprising:disposing a non-heat conductive material about at least a portion of athermal conduit; wherein the thermal conduit comprises a member having afirst end and, a second end; thermally connecting the first end of thethermal conduit to a heat producing device; and thermally connecting thesecond end of the thermal conduit to a heat dissipating device.
 8. Themethod of claim 7, wherein the non-heat conductive material is selectedfrom the group of materials consisting of: a woven fiberglass material,a woven silica material, a woven mineral wool material, a foil backedwoven fiberglass material, a foil backed woven silica material, and afoil backed woven mineral wool material.
 9. The method of claim 7,wherein the non-heat conductive material comprises a coating disposed atleast partially about the thermal conduit.
 10. The method of claim 7,wherein the heat dissipating device comprises a passive radiator. 11.The method of claim 7, further comprising: disposing a wicking materialabout at least a portion of the interior of the thermal conduit; anddisposing a heat transfer fluid within at least a portion of the thermalconduit.
 12. A heat transfer system; comprising: a heat producing devicedisposed at least partially within an electronic device enclosure; aheat dissipating device disposed at least partially within theelectronic device enclosure; a thermal conduit having a first end and asecond, end; wherein a non-heat conductive material is disposed at leastpartially about at least a portion of the thermal conduit; wherein thefirst end of the thermal conduit is thermally connected to the heatproducing electronic device; and wherein the second end of the thermalconduit is thermally connected to the heat dissipating device.
 13. Thesystem of claim 12, wherein the non-heat conductive material comprises amaterial selected from the group of non-heat conductive materialsconsisting of: a flexible non-heat conductive material disposedhelically about the thermal conduit, a non-heat conductive coatingdisposed about the thermal conduit, and a non-heat conductive sleevedisposed about the thermal conduit.
 14. The system of claim 12; whereinthe electronic device enclosure comprises an enclosure disposed at leastpartially about a computing device; wherein the heat producingelectronic device comprises an integrated circuit; and wherein the heatdissipating electronic device comprises an extended-surface radiator.15. The system of claim 12 further comprising an air mover having an airdischarge wherein at least a portion of the air discharge passes acrossthe heat dissipating device.